<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>css三角强化</title>
    <style>
        .box{
            width: 0;
            height: 0;
            /* border-top: 100px solid transparent;
            border-right: 50px solid seagreen;
            border-bottom: 0 solid lightblue;
            border-left: 0 solid lightcoral; */

            /* 只保留右边的边框有颜色 */
            border-color: transparent red transparent transparent;
            border-style: solid;
            border-width: 100px 50px 0 0 ;
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>